An increased emphasis on sustainability, eco-efficiency, and green chemistry has driven a search for renewable and environmentally friendly resources. Starch is a biodegradable polysaccharide, produced in abundance at low cost, which exhibits thermoplastic behaviour. Therefore, it has become one of the most promising candidates for an alternative material to replace traditional plastics in certain market segments such as the food packaging industry.
Numerous studies have been conducted to optimize the performance of starch-based plastics (Mali, S. et al. (2004), Food Hydrocolloids, 19 (2005), 157-164); Soest, J. et al. (1997), Trends in Biotechnology, 15(6), 208-213; Fama, L. et al., LWT, 38, 631-639; Lawton, J. W. (1996), Carbohydrate Polymers, 29 (1996), 203-208). These studies have shown that important properties for evaluation of a packaging material include mechanical properties, gas and water vapour permeability, thermoforming properties, resistance, transparency, and availability (Weber, C. et al. (2001), Food Additives and Contaminants, 19, Supplement, 172-177).
However, the design and engineering of a starch-based packaging product that possesses all of these required properties is a significant challenge. Difficulties are encountered with cost, technical hurdles such as brittleness associated with high loads, and poor water and gas barrier properties which must be overcome to commercialize the biomaterial (Lorcks, J. (1997), Polymer Degradation and Stability, 59 (1998), 245-249).
Other studies have modified the functional properties of starch to enhance its inherent bonding strength by focusing on incorporating additives such as plasticizers to improve the performance of the material (Poutanen, K. et al. (1996), TRIP 4-4 (1996), 128-132; Laohakunjit, N. et al. (2003), Starch, 56 (2004), 348-356).
It has also been reported that certain fungi have the ability to produce exo-polysaccharides that have great potential for use in cosmetic and food industries because of their bioactive characteristics, rheological behavior, and high stability at high temperature (Selbmann, L. et al. (2003), Antonie Van Leeuwenhoek, 84 (2003), 135-145).